1. Technical Field
The present invention relates to liquid ejecting apparatuses equipped with a piezoelectric element that includes electrodes and a piezoelectric layer to generate a change in pressure of a pressure generation chamber communicating with a nozzle opening, and also relates to control methods of liquid ejecting heads.
2. Related Art
As a typical example of liquid ejecting heads mounted in liquid ejecting apparatuses, there is provided an ink jet recording head, for example, in which a part of a pressure generation chamber that communicates with a nozzle opening for discharging ink droplets is configured with a vibrating plate, and this vibrating plate is deformed by a piezoelectric element and pressurizes ink in the pressure generation chamber so as to discharge the link through the nozzle opening as an ink droplet.
As a piezoelectric element used in a liquid ejecting head, there is provided such an element that is configured by sandwiching a piezoelectric material which has an electromechanical conversion function, for example, a piezoelectric layer made of a crystallized dielectric material, between two electrodes. Such piezoelectric element is mounted in a liquid ejecting head as a flexural vibration-mode actuator, for example. Note that, as a typical example of the liquid ejecting head, there exists an ink jet recording head, for example, in which a part of a pressure generation chamber that communicates with a nozzle opening for discharging ink droplets is configured with a vibrating plate, and this vibrating plate is deformed by the piezoelectric element and pressurizes ink in the pressure generation chamber so as to discharge the ink through the nozzle opening as an ink droplet.
A piezoelectric material that is used as a piezoelectric layer constituting such piezoelectric element is required to have an excellent piezoelectric characteristic, and as a typical piezoelectric material, lead zirconate titanate (PZT) can be cited. However, in view of an environmental problem, a piezoelectric material without containing lead or a piezoelectric material whose lead content is suppressed has been required. As a piezoelectric material without lead, for example, a material having a bismuth titanate-based perovskite crystal structure is proposed (for example, see JP-A-2004-6722).
However, there has been a problem that such piezoelectric layer made of a complex oxide without lead or with a suppressed lead content, in particular, a barium titanate-based piezoelectric material depends on an operational ambient temperature in terms of characteristics so that its displacement amount fluctuates largely depending on the operational ambient temperature.
Of course, not only the ink jet recording head, but also other types of liquid ejecting heads that discharge a liquid other than ink have the same problem; in addition, the same problem also occurs in piezoelectric elements that are used in other apparatuses than the liquid ejecting head.